In 2010, Russia baked through its most intense heat wave in recorded history, one that killed over 55,000 people. At the same time, intense rains deluged Pakistan, bringing that nation its worst natural disaster in its history. The following year, it was the United States' turn for extreme heat, as the nation sweltered through its third hottest summer on record, and Oklahoma suffered the hottest month any U.S. state has ever recorded. The U.S. summer of 2012 was even more extreme. Only the Dust Bowl summer of 1936 was hotter, and drought conditions were the most extensive since the 1930s. All of these events--and many more unusually extreme summer months in recent decades--had a common feature, said scientists at the Potsdam Institute for Climate Impact Research (PIK) in Germany, in a research paper published in March 2013 in Proceedings of the National Academy of Sciences. According to the authors, "each time one of these extremes struck, a strong wave train had developed in the atmosphere, circling the globe in mid-latitudes. These so-called planetary waves are well-known and a normal part of atmospheric flow. What is not normal is that the usually moving waves ground to a halt and were greatly amplified during the extreme events. Looking into the physics behind this, we found it is due to a resonance phenomenon. Under special conditions, the atmosphere can start to resonate like a bell. The wind patterns form a regular wave train, with six, seven or eight peaks and troughs going once around the globe". Using a complex theoretical mathematical description of the atmosphere and 32 years of historical weather data, the scientists showed that human-caused global warming might be responsible for this resonance phenomenon, which became twice as common during 2001 - 2012 compared to the previous 22 years.

Figure 1. Drought-damaged corn in a field near Nickerson, Nebraska, Aug. 16, 2012. The great U.S. drought of 2012 was the most extensive U.S. drought since the 1930s Dust Bowl. Damage from the 2012 drought is at least $35 billion, and probably much higher. The associated heat wave killed 123 people, and brought the U.S. its second hottest summer on record. (AP Photo/Nati Harnik)

Figure 2. Business was slow at the Lake Conroe, Texas jet ski rental in 2011, thanks to the great Texas drought and heat wave of 2011. Texas endured its driest 1-year period on record in 2011, and had the hottest summer ever recorded by a U.S. state. July 2011 in Oklahoma was the hottest month any U.S. state has ever recorded, and the contiguous U.S. had its third hottest summer on record. The total direct losses to crops, livestock and timber from the drought, heat wave, and record fires of the summer of 2011 are estimated at $12 billion, with a death toll of 95. Image credit: wunderphotographer BEENE.

Figure 3. Tourists wear protective face masks as they walk along the Red Square in Moscow, Russia on Aug. 6, 2010. Moscow was shrouded by a dense smog that grounded flights at international airports and seeped into homes and offices, due to wildfires worsened by the city's most intense heat wave in its history. The heat wave and fires during the summer of 2010 killed over 55,000 people in Russia and decimated the Russian wheat crop, causing global food prices to spike. (AP Photo/Mikhail Metzel)

Two fundamental atmospheric flow patterns may be resonating more often due to global warmingEarth's atmosphere has two fundamental patterns. One is a series of wave-like troughs and ridges in the jet stream called planetary (or Rossby) waves, which march west-to-east at about 15 - 25 mph around the globe. The other pattern behaves more like a standing wave, with no forward motion, and is created by the unequal heating of the equatorial regions compared to the poles, modulated by the position of the continents and oceans. A number of papers have been published showing that these two patterns can interact and resonate in a way that amplifies the standing wave pattern, causing the planetary waves to freeze in their tracks for weeks, resulting in an extended period of extreme heat or flooding, depending upon where the high-amplitude part of the wave lies. But what the Potsdam Institute scientists found is that because human-caused global warming is causing the Arctic to heat up more than twice as rapidly as the rest of the planet, the two patterns are interacting more frequently during the summer. During the most recent eleven years, 2002 - 2012, there were eight Julys and Augusts that showed this unusually extreme resonance pattern (this includes the U.S. heat wave of July - August 2012.) The two previous eleven year periods, 1991 - 2001 and 1980 - 1990, had just four extreme months apiece. Global warming could certainly cause this observed increase in the resonance phenomenon, but the researchers cautioned, "The suggested physical process increases the probability of weather extremes, but additional factors certainly play a role as well, including natural variability. Also, the 32-year period studied in the project provides a good indication of the mechanism involved, yet is too short for definitive conclusions. So there's no smoking gun on the table yet--but quite telling fingerprints all over the place."

Figure 4. The northward wind speed (negative values, blue on the map, indicate southward flow) at an altitude of 300 mb in the mid-latitudes of the Northern Hemisphere during July 2011 and July 1980. July of 2011 featured an unusually intense and long-lasting heat wave in the U.S., and the normally weak and irregular waves (like observed during the relatively normal July of 1980) were replaced by a strong and regular wave pattern. Image credit: Vladimir Petoukhov.

CommentaryThe new Potsdam Institute paper gives us a mathematical description of exactly how global warming may be triggering observed fundamental changes in large-scale atmospheric flow patterns, resulting in the observed increase in unusually intense and long-lasting periods of extreme weather over the past eleven years. The paper also adds important theoretical support to the research published in 2012 by Dr. Jennifer Francis of Rutgers University, which found that the amplitude of Earth's planetary waves had increased by over 100 miles (161 km) in summer over the past decade in the Northern Hemisphere. Dr. Francis theorized that this change was connected to increased heating of the Arctic relative to the rest of the Earth, due to the observed decline in late spring Northern Hemisphere snow cover. Humans tend to think linearly--one plus one equals two. However, the atmosphere is fundamentally non-linear. What may seem to be modest changes in Earth's climate can trigger unexpected resonances that will amplify into extreme changes--cases where one plus one equals four, or eight, or sixteen. In some cases, when you rock the boat too far, it won't simply roll a bit more, it will reach a tipping point where it suddenly capsizes. Similarly, human-caused global warming is capable of pushing the climate past a tipping point where we enter a new climate regime, one far more disruptive than what we are used to.

Julys and Augusts since 1980 when quasiresonant extreme conditions were observedThe Potsdam Institute's research lists sixteen July and August periods since 1980 that have had extreme atmospheric flow patterns due to quasiresonance. These months featured severe regional heat waves and destructive floods in the Northern Hemisphere midlatitudes, detailed below. Half of these months occurred in the most recent 11-year period, 2002 - 2012. During most of these extreme months, there was not a moderate or strong La Niña or El Niño event contributing to the extremes. Summers when a La Niña or El Niño event was present are listed in parentheses, based on the Oceanic Niño Index (ONI).

July and early August 2012: Catastrophic floods in China and Japan, as well as record-breaking temperatures during heat waves in the United States and southern Europe (weak summer El Niño)

July 2011: Record heat wave in the United States, resulting in the fourth warmest July on record nationally and the driest conditions in the southern United States ever (weak summer La Niña)

July/August 2010: Russian heat wave and the Pakistan flood, with the strongest and most persistent extreme weather conditions and the highest death tolls from heat waves and floods ever for these two regions (strong summer La Niña)

July 2006: Temperatures higher than 100°F for only the second time in Britain’s history and much of Europe experiencing a serious heat wave (weak summer El Niño)

August 2004: Much of northern Europe hit by very low winter-like temperatures and sporadic snowfalls (moderate to strong summer El Niño)

July 2000: Destructive floods in northern Italy and the Tisza basin and a simultaneous heat wave in the southern United States, smashing all-time high-temperature records by that time at many sites (strong summer La Niña)

July/August 1997: Disastrous Great European Flood, which caused several deaths in central Europe, and the destroying floods in Pakistan and western United States (strong summer El Niño)

July 1994: Very strong heat wave in southern Europe, with a national temperature record of 47.2°C set in Spain (weak summer El Niño)

July 1993: Unprecedented great flood in the United States that reigned over the country from April (weak summer El Niño)

July 1989: Unusually intense and unprecedented widespread drought in the United States (weak summer La Niña)

August 1987: Severe drought in the southeastern United States (strong summer El Niño)

August 1984: Continuation of the severe heat of summer 1983, with serious drought in the United States (weak summer La Niña)

July and August 1983: Very dry conditions, severe heat, and substandard crop growth (5–35% below normal) in the Midwest United States (weak summer El Niño)

Press release issued in March 2013 by the Potsdam Institute for Climate Impact Research (PIK), "Weather extremes provoked by trapping of giant waves in the atmosphere."

In this 40-minute lecture presented in 2013 at the University of Arkansas, Dr. Jennifer Francis of Rutgers University explains the linkage between warming in the Arctic due to human-caused global warming and an observed shift in Northern Hemisphere jet stream patterns.

Quoting TomTaylor:Well I understand the whole gradient concept, but we must keep in mind exactly where we want the gradient. For tornadoes, you'd want warmth in the SE and cold in the northern Plains and Rockies. That way, when you get the CAA and WAA around the low pressure system, you get a stronger clash between these regions which are already naturally warmer (referring to the SE) and colder (referring to the northern Plains/Rockies) relative to each other.

So if it's cold right now in the East and SE, that would not at all be beneficial for tornadoes. If anything, this weakens the temperature gradient since this is supposed to be the warm region. Cold in the SE would also cool the gulf...cooling the gulf limits both warmth in the SE and moisture availability, as I'm sure you already know.CFS Reanalysis Month Temperature Anomaly

GFS Week 1 Temperature Anomaly

Yup, that somes it up. Looks like no significant severe weather events until April maybe May.

Quoting TropicalAnalystwx13:Forgive my lack of logic on this lol, but how does which way the gradient is facing affect whether the tornado season is active [or not]? There's still the clashing of two air-masses somewhere.

Well, first of all, it's very hard to get an air mass that is significantly colder in the deep south than it is in the midwest.

Secondly, if somehow such a gradient were to be established, it would moderate very quickly due to ground temperature. Also, such a gradient, if large-scale, would not be dynamically favorable for severe thunderstorms, since it would cause a dramatic weakening of the polar jetstream over the U.S., and cold, dry air would cut off the flow of moist, tropical air from the Gulf of Mexico. Unless you reverse Earth's natural thermodynamic state, this isn't going to favor severe weather outbreaks.

Get collapses&landslides from all the crude being pumped outta there.Thought I'd read that there's a Gulf subduction zone, but googling awhile back trying to find more specific info didn't get me any results.

20 Years ago tomorrow the 1993 Storm of The Century was preparing to unleash a squall line with severe winds, tornadoes and Storm Surge on Florida as it pounded the NE with heavy winds, snow and blizzard conditions.

OK and you can have; Texas Flood by SRV and Dust Bowl Blues by Woody Guthrie.How do you you get those links in blue to work? Or is it a secret imparted by Grother in one of his earlier incarnations? Or was it a momentary lapse of reason when somebody called Floyd might have cited in Pink!Anybody heard from Patrap?Toasted Cheese Sandwich time here and the weather chap for the next installment.

Quoting TropicalAnalystwx13:I heard it from Ryan Maue last month. Don't know the specifics, but it makes sense to me given that a larger gradient between cold and dry and warm and moist causes thunderstorms to build.

Well I understand the whole gradient concept, but we must keep in mind exactly where we want the gradient. For tornadoes, you'd want warmth in the SE and cold in the northern Plains and Rockies. That way, when you get the CAA and WAA around the low pressure system, you get a stronger clash between these regions which are already naturally warmer (referring to the SE) and colder (referring to the northern Plains/Rockies) relative to each other.

So if it's cold right now in the East and SE, that would not at all be beneficial for tornadoes. If anything, this weakens the temperature gradient since this is supposed to be the warm region. Cold in the SE would also cool the gulf...cooling the gulf limits both warmth in the SE and moisture availability, as I'm sure you already know.CFS Reanalysis Month Temperature Anomaly

I wonder if the drought across the MidWest & Western US are altering the Jetstream some as it appears the EAST is locked into this trough for several more weeks to come. I also wonder if this will be a permant feature for the rest of this Spring. If this is the case then Tornado season will be a bust this year.

Quoting PlazaRed:Probably estuary mud sediment which settles in low movement waters a bit like you get in the bottom of mop buckets when you haven't used them for a while.That's how it would appear in these estuaries, which haven't been stirred up for a few years and are full of all sorts of decaying vegetation and human waste polution, general trash and discarded artifacts,certainly not oil as they would first be moaning about it, them refining it. I dont think Japan has much or any oil, as its a volcanic ridge anomaly.

oil? certainly not it is... only for it's black dense look...

Yeah that decaying waste on there is disgusting... and must smelllll.....I feel really bad for those who faced death.

Quoting Tropicsweatherpr:The March update by ECMWF of the Mean Sea Level Pressures (MSLP) for July,August and September shows normal pressures in the North Atlantic basin and if that forecast holds,that would be worrisom in terms of threats to the Caribbean and Gulf of Mexico.Is a very significant difference in the March European forecast for March 2013 vs. March of 2012. Last year, the Euro was forecasting very high pressures across the deep tropics. (and most storms formed in the subtropics)

March 2012 forecast for July,August and September.

March 2013 forecast for July,August and September.

No fair, it's not updated for me yet for some reason. Even URL hacking doesn't work.

Only if the gradient is oriented properly. Tornado season is enhanced by a southward or southeastward-pointing temperature gradient. In other words, colder than normal to the north or northwest, and warmer than normal to the south or southeast.

Forgive my lack of knowledge on this lol, but how does which way the gradient is facing affect whether the tornado season is active [or not]? There's still the clashing of two air-masses somewhere.

Probably estuary mud sediment which settles in low movement waters a bit like you get in the bottom of mop buckets when you haven't used them for a while.That's how it would appear in these estuaries, which haven't been stirred up for a few years and are full of all sorts of decaying vegetation and human waste polution, general trash and discarded artifacts,certainly not oil as they would first be moaning about it, them refining it. I dont think Japan has much or any oil, as its a volcanic ridge anomaly.

Quoting TropicalAnalystwx13:I heard it from Ryan Maue last month. Don't know the specifics, but it makes sense to me given that a larger gradient between cold and dry and warm and moist causes thunderstorms to build.

Only if the gradient is oriented properly. Tornado season is enhanced by a southward or southeastward-pointing temperature gradient. In other words, colder than normal to the north or northwest, and warmer than normal to the south or southeast.

Well it reaches the point where you cant agree any more, then I read this from the blog heading post:-

"What may seem to be modest changes in Earth's climate can trigger unexpected resonances that will amplify into extreme changes--cases where one plus one equals four, or eight, or sixteen. In some cases, when you rock the boat too far, it won't simply roll a bit more, it will reach a tipping point where it suddenly capsizes."

I think that the rocking of the boat was quite a while ago now and we are suffering the consequences of it past tense 'capsize.'Then again I could be wrong.Apparently the rain is going to stop here on Wednesday for a few days! not that 9 inches in a day is out of the ordinary now, its just that nobody had ever seen it before. In living memory that is.

The March update by ECMWF of the Mean Sea Level Pressures (MSLP) for July,August and September shows normal pressures in the North Atlantic basin and if that forecast holds,that would be worrisom in terms of threats to the Caribbean and Gulf of Mexico.Is a very significant difference in the March European forecast for March 2013 vs. March of 2012. Last year, the Euro was forecasting very high pressures across the deep tropics. (and most storms formed in the subtropics)

Speaking of black socks and shorts, reminds me of a scientist I once worked with almost 25 years ago. We were doing some extensive radar performance testing on a Navy Cruiser. During the transit of the Panama Canal, we had a few hours to be tourists and enjoy the scenery. Then along comes Lennie, attired in some Gosh-Awful plaid shorts and black socks. To make matters worse he was carrying a plastic shopping bag with 3 cameras. When asked why he had 3 cameras, his reply was; "Only one of them works and I can't remember which one."

His adventures didn't end that night. After the ship docked and we had all had a good dinner, Lennie decided to wander around the perimeter of the Naval Base looking for exotic flora and fauna, when he was accosted and nearly shot by the Marine guards on duty.

Quoting PalmBeachWeather:See it all the time here in Florida... Black socks, and the "MUST" camera... So freekin' cool

Speaking of black socks and shorts, reminds me of a scientist I once worked with almost 25 years ago. We were doing some extensive radar performance testing on a Navy Cruiser. During the transit of the Panama Canal, we had a few hours to be tourists and enjoy the scenery. Then along comes Lennie, attired in some Gosh-Awful plaid shorts and black socks. To make matters worse he was carrying a plastic shopping bag with 3 cameras. When asked why he had 3 cameras, his reply was; "Only one of them works and I can't remember which one."

His adventures didn't end that night. After the ship docked and we had all had a good dinner, Lennie decided to wander around the perimeter of the Naval Base looking for exotic flora and fauna, when he was accosted and nearly shot by the Marine guards on duty.